﻿// Spun AJAX Framework
// Copyright (C) 2008 Blake Hegerle
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace Formality.FormalSystem
{
    public class Bindings
    {
        public Bindings()
            : this(null)
        { }

        public Bindings(Bindings Bindings)
        {
            BindingMap = new Dictionary<string, Variable>();
            this.ParentScope = Bindings;
        }

        public Variable this[string Name]
        {
            get
            {
                Variable Var;

                if (BindingMap.TryGetValue(Name, out Var))
                    return Var;

                if (ParentScope != null)
                    return ParentScope[Name];
                else
                    return null;
            }

            set { BindingMap[Name] = value; }
        }

        public override string ToString()
        {
            var Buffer = new StringBuilder();

            foreach (var Binding in BindingMap)
                Buffer.AppendFormat("{0}={1} ", Binding.Key, Binding.Value.BindingNumber); 

            return Buffer.ToString();
        }

        private Bindings ParentScope;
        private Dictionary<string, Variable> BindingMap;
    }
}
